Fractionating column



' Feb'. 25, 1930.

R. B. ClllLLAS,'JR., ET AL FRAGT I ONATING COLUMNV Filed Nov. 24, 1925`2.45 i 'y thefliquid-` and its return to'liquid through Pat'fnted Feb.25, 1930 UNITED STATES PATENT, o l-FICE RICHARD B." CHILLAS, JR., OFPHILADELPHIA, AND ALBERT G. PETERKIN, JR., 0F BRYN MAWR, PENNSYLVANIA,ASSIGNORS T THE ATLANTIC REFIN ING COMPANY, OF PHILADELPHIA,PENNSYLVANIA, A CORPORATION OFv PENNSYLVANIA rnAoTIoNATING COLUMN"AApplication filed November 24, 1925, Serial No. 71,165.

Our invention relates to fractional distillation ofliquids, especiallycrude petroleum,

petroleum distillate or residuum, and relates more particularly toimprovements in f ractionating columns of the bubbler plate, sieve lplate or equivalent plate type.

In 'accordance with our invention, spray,

liquid particles or mist entrained in and transported by the` vaporascending inthe 10'column isl prevented from reaching and contaminatingliquid of lower boiling point by separatingthe spray, particles or mistfrom theyvapo'r. in each` of the several successive inter-plate chambersor zones, and returning the separated liquidl tothat through which thevapor'has passed. v

In accordancelwith our invention, the sepa- Iration of entrained'li'quidfrom the vapor is edeoted, without recourse to checker work or columnpacking, by disposing in the vapor path between successive bubbler,sieve or equivalentv plates liquid-separating structure, such as. haineplates,lagainst which the vapor with its cntrained liquid imp inges andof a form or `dispo'sitionto cause separation of whichthevaporfhaspreviously passed. l

1 In accordance withjpur invention, because of separationl of' entrainedliquid' from the vapor, the velocity ofthe vapor through thefractionating colurnmay be materially higher than in prior ractic'e,with resultant increase inthe rate 'o y flow of vapor through 'thecolumn andconsequent increase of capacity 4of ythe `ccilumnyi.- er,increasel in thev vapor Our inventionfresides in apparatus'of thecolumn, passes upwardlythrough successive .vertically spacedjjp'lates,bubbling through pools oE reflux liquid on eachplate, tocauseinterchangey of constituents, vsome of the higher boiling components inthe vapor phase being `condensed 'and thereby liberating' their latentheat ofvaporization which v aporizes lower boiling components of theliquid. In consequence, in progressing upwardly through the column thevapor becomes richer in low boilin constituents at the expense of thehigher bolling components.

is in a state of! agitation, more or less violent, and a portion of theliquid becomes entralned by thev vapor and is transportedupward'therewith as liquid spray, drops orA mist.A Some ofthe liquidparticles fall back on to the plate, while others are transported by thevapor throughthe plate above into contact with theliquid thereon,thereby contaminating the. liquid on the upper plate ,75

witlrthe higher boiling liquid from the lower plate. The amount ofliquid so entrained by the ascending vapor is dependent upon themagnitude of the vapor velocity through the adjacent its bottom.. Inoperacolumn, and particularly through'the li uid pools overlying-theplates therein, an in;

consequence the vapor .velocity practicable orfall'owablewith agivencolumn limits itscapacity, the frate' of :flow of f vapor there-`through andthe rate of fractionation ef-` fectedj'thereby.,l Therefore,Itor any vcoluin'n',j y t .themaxlmum quantity of'vaporwhich maybefoperated upon'- therein is such that the va- Y por velocity doesv notattain that magnitude at whichth'eentrainment .of liquid beginsto lbecome significant. w

It iis .the .object of. `.ou'r 'prove uponsuch' prior practicebyfseparating the entrained liquid from the vapor, and moreparticularly, bjr-increasing thevap'or velocity andfse'parating from thevaporl the liquidparticlesv incident to the increased velocity.

For an understanding of our-method, and

y 9o inventionr to, imf for an illustration ofjsome ofi-thel variousforms our structure may take, reference is" j ating column or tower,

Fig. 1a is a fragmentary vertical sectional view of a modification.

Fig. 2 is a vertical sectional view, partly in elevation, on enlargedscale, of structure of the-character shown in Fig. 1.-

' Fig. 3' is a horizontal sectional view, partly in plan, taken on theline 3-3 of Fig. 2.

Fig. 4 is a fragmentary vertical sectional' view, partly in elevation,of a column. in which the baille structure comprises a continuous'plateprovided with vapor-passing structure.

Fig. 5 is a hori-zontal sectionalview, partly inplan, takenl on the line5-5 of Fig. 4.

Referring to Fig. l C represents fractionas of sheet metal, intowhich-there is delivered through the-pipe 1 adjacent its lower end thevapors of the liquid to be fractionated. The pipe 1 may be the vaporlinefrom a pipe still or other form of still in which ,there is vaporizedcrude petroleum, petroleum distillate, or petroleum residuum.Communicating with the column adjacent its upper end is the pipe 2,through which is drawn off to a condenser the fractionated vapor, a partof whose condensate is returned through the pipe 3 into the colec umn,adjacent its upper end, as reflux liquid which descends through thecolumn and which, finally-enriched by higher boiling point constituents,is drawn od adjacent the lbottom of the column through the pipe 4.

Suitably spaced from each other vertically in the column C. are thefractionating plates F, of any suitable charactensuch as the sieve,bubbler or equivalent type. In the example illustrated, the plates areof the bubbler-cap type having the upwardly extendingl vapor uptakes orports v extending slightly above the plates F and discharging under thecaps c discharging at d through' the reflux liquid on'the upper sides ofthe plates F, the liquid depth ybeing determined by the height above theplates the reliux conducting tubes t, whose'lower ends discharge thereflux liquid on to" and adjacent the fractionating plate F below.

formed 'an interplate chamber or zone V Between' neighboring plates FVthere is through which the vapor, after passing through or contactingwith the reflux liquid Aupon a lower plate, ascends, passing up throughthe vapor uptakes or ports 'u of the plate above. l

Because of its contact with the reilux liquid upon the plates F, thevapor current entrains the reflux liquid in the form of spray, drops,particles or mist, and vtransports them to the refluxv liquidon theplate above, causing contamination of the upper reflux liquid and vapor.

of the upper ends of f j baille plates pool of liquid with higherboiling point constituents from the pool below. The quantity of liquidso entrained increases with increase in .velocity of the vapor, andtherefore, with the quantity of vapor owing through the column per unitof time, that is, upon the rate of vapor flow through the column. Inconsequence, the ca acity of the column is adocted and limited y theamount of liquid entrained, or by the vapor velocity. Accepted practicelimits this velocity' to about 1.3 to about 2 feet per second, dependingin part uppn the distance between the fractionating plates and basedupon the'total cross section of the column.

. To utilize a vapor velocity which is materially higher than 'commonlyheretofore utilized, thus increasing the capacity of the column, is anobject of our invention, and to this end we dispose between neighboringfracvtionating plates or 1n the inter-plate chamber lthe ascending vaporstream impinges, causing the entrained liquid particles to impinge uponthe structure and separate from the vappr and to return to a lowervreflux liquid poo This liquid-separating structure, in accordance withour invention, is to be distinguished from packing or checker work whichfrequently has been used in fractionating columns to increase the areaof contact between In our system we employ for the vapor therefore forthe fractionation, plates of any of the well'known forms, but interposebetween these plates baiile members which serve only for the collectionof entrained liquid and which do not materially diminish the vapor spaceof the column, avoiding therefore any considerable increase in vaporvelocity per liquid contact, and

se. The members are so placed that the main fr streams of liquiddescendinor through the. column, as through the tubes t, do not flow'IIn the example illustrated in Fig. 1, the ,v

liquid-separating or baille structure comprises a plurality ofsubstantially parallel inclined b carried by a. ring or frame f restingupon abutments a carried by the column C. Between the plates b areformed upwardly inclined passages through whichwi4 ,the vapor ascends,and`in passing impinges upon the plates I), causing separating of liquidwhich collects upon the plates; and

flows downwardly along them back into thel reflux pool upon the plate Fbelow. Neigh boring plates b are so' spaced from each other and soinclined that the upper edge of laterally overlaps the lower edge centplate b, whereby the majdrportion of the entrained liquid is broughtinto contact with eachl of the adjailo iao

the balile plates b, since there is no passage through which the vaporand entra-ined liquid Amay rise vertically unhindered or without cominginto contact with baille plate structure.

With a construction of the character described, vapor-.entering thecolumn C through the -pi e 1 passes upwardly in succession throug 1 thefractionating p ates F andthe reflux liquid pools thereon. The vaporpassing rapidl throughthe reflux liquid entrains particles thereof whichare subsequently projected against the inclined baille surfaces and dropback to the reflux liquid on the plate below,j with the result that thevapor reaching the .fractionating plate above is relatively dry, in thesense that it is substantially free of liquid particles. In the exampleillustrated in Fig. 1, there is provided in each inter-plate space asecond baille structure similar-to that described vand superposedthereon. This second baille struc` ture comprises a ring or frame f1carrying the balile plates b1, inclined reversely -with respect to thelower baille lates b with the' passages between them formmgcontinuations of the vpassages between the lower plates b and inclinedupwardly in opposite sense. 7

The principle remains vthe Same, however, but there is afforded by thisadditional structure additional. liquid-separating capacit the reverseinclination of the upper ba e plates b1 havin' some advantage over thecase where the ower ballles b. are simply of increased extent.-

In Fig. ll'a generally similararrangement is shown, except that theyframesorl rings f and f1 andthe bale plates Inv and b1' carried by themare spaced vertically from each other. 1 q p In Figs. 2 and 3 thearrangement is in gener'al that described in connectionfwith Fig. 1,.there being illustrated in this instance the brackets @securedtothe ringf and tothe individual baille platesv orslats b .at their opposite ends.In Fi .3 there is well-'illustrated the overlap of e upper edges 'ofthev plates blaterally ofthe lower edges-of the l next adjacent lates. 1

In lthe mod1fcation illustrated injFigs. 4 1 and 5, the bale structurecomprises a continuous or solid plate jdis osed between nei hboring.fractmnatingj-p ates F 'and provi ed with any suitable number oflvapor'guptakes or ports fv, above which are disposed the caps orcoversle supported by legs or columns m l upon the plates j. f Hereagain the ascendingvapor impinges upon the under sides ofthe covers lc,caiismg separation of the entrainedlliquid which falls upon the platesj, while the vapors vcontinue upwardly through the inter-plate zone or camber V through the passages c in the plate above. The separated -liquidcollects u on I 55v the plate .j and flows.downwardly throug `a fmakespossiblel t columnof a given size.

the balile structures shown in the drawings `In -our coip 71,093', filedlmethod of 'fractionation herein disclosed.

tube o to re-join the reflux liquid on the late F below.\ As indicated,the reflux con ucting tubes t extend through and are spaced from thetubes o. i

. It is characteristic of all the arrangements shown, and of ourinvention, that the liquid entrained in the vapor strikes theseparatorstructure or haines, is deflected from its course and is returned to thereflux liquid on a lower fractionating plate, while the relatively dvapor asses on upwardly through the co umn. ubstantially no liquid iscarried froml any fractionating plate to the reflux liquid upon afractionating plate above, even thoughv the velocity of the vapor may bematerially in excess of that utilized in ordinary practice. We are able,by means o1t` our invention, to maintain vapor velocities considerablyin excess of 3 feet per second and of the order of at least three timesthe accepted standards. For example, our invention readily permits a'vapor velocity of 4 feet per second and We have been able to reachvelocities of 6 feet per second and higher without impairin thefractionation through the carrying o entrained liquid from one plate tothe plate above. Our preferred rate is about 5 feet per second. Thesevelocity figures are based on the total cross sectional area of thecolumn and represent the vertical velocity through a completely freezone of the column. This increase 1n vapor velocit correspondinglyincreases the. ca acity o the column, and

lie fractionation of a larguer quantity of liquid per unit of time witha It will. be understood that our invention is `not limited. as to thetype or character of the liquid vseparating structures employed, thatare exemplary, and that there may be emvployed vany equivalent typeofdevice suitl able in association or combination w1th fracltionatingplatesto separate entrained liquid f from thezvapor.;

v 11o ending application Serial N o. ovember 24, 1925, is claimed the Itwill .further be understood that in the appended-claims the termvfractionating p atei is used generically to include plates ot' the bubbler cap, sieve and equivalent types, of a structure causing thevaporto f .through the refluxing liquid.

pass or bubble :What we claim is: 12o 1. Fractionating apparatuscomprisingxatw column,A fractionatin platesf spaced `from each othertherein, anl between fractionating plates bafile; members whose totalcross sectional area isa relatively small percentage 12: ofthe totalcrosssectional areapof said column, said baillemembersspaced from eachother and inclined with respect to the normal i course of the. vaporrbetween fractionating plates for separating from the vapor andreturning-to a ractionating plate reflux liquid entrained in the vapor.l

2. Fractionating apparatus comprising a column, fractionating platesspaced from Vi each other therein, and means for separating from thevapor rellux liquid entrained therein and for returning the separatedliquid to a fractionating plate comprising a plurality of sets of bailleplates forming passages traversed in successionby the Vapor, the bailleplates of the dierent sets being reversely inclined with respect to thecourse of the vapor. 3. Fractionating apparatus comprising a column,fractionating plates spaced from 5 each other therein, and means forseparating `from the' vapor and returning to a fractionating plate'vreflux liquid entrained in the vapor comprising a plurality of bailleplates spaced from each other and inclined with respect to the course ofthe vapor, the upper end of a baille plate laterally overlapping thelower end of the adjacent baille plate.

4. Fr'actionating apparatuscomprising a column, fractionating plates"spaced from each other therein, a frame disposed between fractionatingplates, anda plurality7 of baille members carried by said frame andinclined withdrespect to the course of the vapor for separatingtherefrom and returning toY a" fractionating plate reflux liquidentrained in the vapor.

- 5. Fractionating apparatus comprising a column, spaced plates thereinupon which liquid entrained in the vapor is removed there from. A

6. Fractionating apparatus comprising a column, means therein defining aplurality o ffractionating zones, and means in at leastv one of saidzones for separating from vapor reflux' liquid entrained in the vaporcomprisinga plurality of baille plate spaced from each other to definepassages for the rising vapor, said plates having such thickness and sodisposed that the velocity of the vapors upon traversing `said passagesis not greatly increased.

7. Fractionating ap aratus comprising a ractionating zones, and means inat least one of said zones for separating fromupwardly assing fluidliquid entrained therein,` said l ast mentioned means comprising bailleplates i". whose total' cross sectional area 1s a relatively downwardly.dropping liquid may collect, means for conducting liquid from one ofsaid at least two of said spaced materially increased and substantiallyall small percentage of the total cro'ss sectional area oi said column,said baille plates forming passages to be traversed in succession by theupwardly passing fluid. l

RICHARD B. CHILLAS, JR. ALBERT G. PETERKIN, Jn.

lso

column, means therein efining a plurality of 'l

